An input/output (I/O) interface is a system that enables the transfer of information between internal storage and external I/O devices. In particular, the I/O interface acts as an interface between the central processing unit (CPU) and memory and to one or more peripherals. In many high-speed I/O circuit designs, several different power supply voltages may be used in order to meet a particular I/O specification. For example, some conventional designs use supply VDDQ ranging from 1.2 volts (v) to 1.5v and core logic positive supply (VDD) ranging from 0.8v to 0.9v. Designing I/O circuits that use different supply voltages can present challenges. Such designs can include the use of both high-voltage transistors and low-voltage transistors.
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